实验性大鼠坐骨神经损伤与再生的病理学观察

目的：研究大鼠坐骨神经钳夹损伤后的病理学改变。方法：建立大鼠坐骨神经钳夹损伤模型,分别于术后１、２、３、４、６周取受损坐骨神经进行光镜电镜和免疫组化观察,用图像分析仪测量３、４、６周及对照组的坐骨神经轴突的等效直径、周长和面积等８项参数。结果：钳夹后１周损伤处远段神经发生华勒变性,钳夹后２周神经纤维再生。再生轴突在第３、４周时与正常轴突有显著差异（Ｐ〈０．０５或Ｐ〈０．０１）,第６周时无显著差异（     

Morphometric and ultrastructural changes with ageing in mouse peripheral nerve

Qualitative and quantitative information is reported on the morphological changes that occur in nerve fibres and nonneuronal cells of peripheral nerve during the lifetime of the mouse. Tibial nerves of mice aged 6–33 mo were studied. With ageing, collagen accumulates in the perineurium and lipid droplets in the perineurial cells. Macrophages and mast cells increase in number, and onion bulbs and collagen pockets are frequently present. Schwann cells associated with myelinated fibres (MF) slightly decrease in number in parallel with an increase of the internodal length from 6 to 12 mo, but increase in older nerves when demyelination and remyelination are common. The unmyelinated axon to myelinated fibre (UA/MF) ratio was about 2 until 12 mo, decreasing to 1.6 by 27 mo. In older mice, the loss of nerve fibres involves UA (50% loss of 27–33 mo cf. 6 mo) more markedly than MF (35%). In aged nerves wide incisures and infolded or outfolded myelin loops are frequent, resulting in an increased irregularity in the morphology of fibres along the internodes. In the mouse there is an adult time period, 12–20 mo, during which several features of degeneration progressively appear, and an ageing period from 20 mo upwards when the nerve suffers a general disorganisation and marked fibre loss.     

海藻纤维膜片促进大鼠损伤坐骨神经的再生

背景：课题组和青岛大学高分子材料研究所合作研制的海藻纤维生物膜,具有优良的生物相容性,常被用作制备各种复合材料。 目的：观察海藻纤维膜片包绕覆盖神经断端吻合口对大鼠坐骨神经损伤后再生的影响。 方法：切断36只雄性Wistar大鼠右侧坐骨神经,随机分组：对照组行神经外膜端端吻合;实验组行神经外膜端端缝合,将海藻纤维膜片包绕并覆盖神经吻合口远近端各约0.5 cm,形成封闭再生室。术后观察海藻纤维膜片降解吸收规律及缝合处粘连情况,组织学切片行苏木精-伊红染色、锇酸染色、白细胞介素2及白细胞介素4免疫组织化学染色。 结果与结论：术后4-6周,实验组海藻纤维膜片逐渐被降解吸收,与周围组织粘连较少,炎性细胞浸润程度较轻,纤维组织增生较少。两组术后1,7,14 d的白细胞介素2及白细胞介素4含量比较差异无显著性意义。实验组术后6周再生神经纤维分布规则且大小较为均一,其神经纤维数量、轴突大小及髓鞘厚度等指标均显著优于对照组(P < 0.05)。表明海藻纤维膜片具有良好的生物降解性和组织相容性,其包绕覆盖坐骨神经形成的神经再生密闭室可促进大鼠损伤坐骨神经再生。中国组织工程研究杂志出版内容重点：生物材料;骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性;组织工程全文链接：     

大鼠肝再生过程中毛细胆管增生的形态计量研究

Morphometric analysis of the liver during regeneration after partial hepatectomy showed that the mean area and number of bile canaliculi increased, while the volume density of microvilli related to the lumina of the canaliculi decreased. These changes were observed 12 hours after the operation, which gradually returned to normal on the third day after operation. It indicated that the decrease of volume density of microvilli was the result of enlargement of bile canaliculi, which was different from the decrease of microvilli due to passive widening of the canaliculi such as in cholestasis from loss of microvilli. All these phenomena suggest that enlargement of the area of bile canaliculi during liver regeneration may be due to the increase of membranous protein synthesis. Moreover, the increase of the number of bile canaliculi suggests that the proliferation of hepatocytes is associated with formation of new branches of bile canaliculi.     

A synthetic oxygen carrier in fibrin matrices promotes sciatic nerve regeneration in rats

Tissue-engineering nerve conduits have been studied for a long time in bridging large nerve defects. However, the low oxygen availability within the nerve conduits, which results in death of migratory Schwann cells (SC) or loss of the newly formed tissue’s function, is still an obstacle for axonal regeneration. Thus, it was hypothesized that an oxygen-enriched conduit would enhance axonal regeneration and functional recovery in vivo. To address this issue, perfluorotributylamine (PFTBA) enriched fibrin hydrogel was prepared and injected into collagen–chitosan conduits. The conduit containing PFTBA-enriched fibrin hydrogel was then used to bridge a 12-mm sciatic nerve defect in rats. The control rats were bridged with collagen–chitosan conduits filled with fibrin matrices without PFTBA. It was found that axonal regeneration and functional recovery in the combined PFTBA group were significantly higher than those in the control group without PFTBA. Further investigations showed that the mRNA and protein levels of S-100, brain-derived neurotrophic factor and nerve growth factor were enhanced by PFTBA at 1 and 3 weeks after surgery. However, the mRNA and protein levels of vascular endothelial growth factor were in a similar range between the combined PFTBA group and the control group without PFTBA. In addition, immunohistochemical results showed that the morphological appearances of regenerated nerve and survival of SC were enhanced by PFTBA at 4 and 12 weeks after surgery. In conclusion, PFTBA-enriched nerve conduit is capable of enhancing axonal regeneration, which provides a new avenue for achieving better functional recovery in the treatment of nerve defect.     

Enhanced intake of ethanol in preweanling rats following interactions with intoxicated siblings

Recently Hunt, Holloway, & Scordalakes (1999) described a novel procedure for examining how social interactions with an intoxicated sibling can enhance periadolescent rats' voluntary intake of ethanol. In the present series of experiments we extend these findings to preweanlings. In Experiment 1, same-sex sibling 16-day-olds were assigned to be either (a) a demonstrator that was administered 1.5 g/kg ethanol or water control or (b) an observer that was tested for ethanol intake following a brief interaction with the demonstrator. Observers interacting with EtOH demonstrators exhibited increased intake of ethanol relative to observers interacting with water demonstrators. In Experiment 2, subjects were 8, 12, or 16 days of age and at all ages, ethanol intakes increased following exposure to an intoxicated sibling. In Experiment 3, repeated exposures to ethanol demonstrators on days 12, 14, and 16 was found to promote ethanol intake after weaning (on postnatal day 22). Collectively these data indicate that exposure to ethanol cues in the context of home/social cues can lead to modifications in ethanol acceptance, and that repeated exposures to such cues during infancy can impact ethanol ingestion after weaning.     

The distribution of peroxidases in the sciatic nerves of normal and hexachlorophene intoxicated developing rats

Summary Horseradish peroxidase (mol. wt. 40 000) or microperoxidase (mol. wt. 1900) were injected over the sciatic nerve of normal or hexachlorophene (HCP) intoxicated developing rats (3,7,14 and 21 days). Light and electron microscopic studies of nerves after histochemical staining for peroxidase revealed: a) the perineurial barrier to the two peroxidases was established in 21 day normal and HCP intoxicated rats; b) in animals 3–14 days, the perineurial barrier to both peroxidases was not formed and peroxidase staining was observed in the periaxonal space and in the space between paranodal loops of myelin; c) intramyelinic vacuoles, induced by HCP in animals 7–14 days did not show peroxidase staining. HCP-induced intramyelinic vacuolation is due to the separation of the myelin lamellae at the intraperiod line; although these vacuoles are potential extensions of the extracellular space, they are not stained with the extracellular markers horseradish or microperoxidase.This paper was presented in part at the 51st Annual Meeting of the American Association of Neuropathologists, 30 May–1 June, 1975, New York.     

胆囊收缩素促坐骨神经再生的可能机制

背景：前期实验发现,八肽胆囊收缩素能促进大鼠坐骨神经损伤后的再生,但具体机制仍不清楚。目的：筛选有效指标,尝试从神经生长因子及神经再生微环境的角度分析八肽胆囊收缩素促进大鼠坐骨神经再生的机制。方法：选择健康SD大鼠,制备坐骨神经单侧离断伤模型后随机分为2组,八肽胆囊收缩素治疗组造模后连续7 d腹腔注射八肽胆囊收缩素8 nmol/kg,对照组腹腔注射等量生理盐水。检测两组大鼠局部神经生长因子蛋白表达、脊髓诱导型一氧化氮合酶水平、血清超氧化物歧化酶活性和丙二醛浓度,同时检测脊髓凋亡细胞数。结果与结论：八肽胆囊收缩素治疗组大鼠局部神经生长因子蛋白表达高于对照组(P < 0.01),脊髓诱导型一氧化氮合酶和凋亡细胞数低于对照组(P < 0.01),血清超氧化物歧化酶活性高于对照组且丙二醛浓度低于对照组(P < 0.01,0.05)。说明胆囊收缩素促进坐骨神经再生的可能机制包括保护神经元、抗细胞凋亡、抑制炎性反应、抗NO及氧化反应、抗丙二醛减轻自由基损伤等方面外,还可刺激神经生长因子的表达和释放。 中国组织工程研究杂志出版内容重点：组织构建;骨细胞;软骨细胞;细胞培养;成纤维细胞;血管内皮细胞;骨质疏松;组织工程全文链接：     

Experimental rabies: ultrastructural quantitative analysis of the changes in the sciatic nerve

To study the pathology of peripheral nerves in experimental rabies infection, street rabies virus ws inoculated into the right footpad of two groups of mice, A and B, which received, respectively, 10(4.5) LD50 and 10(3.5) LD50 of the virus. Paralysis was observed in 60% of animals of group A and 20% of group B. The main ultrastructural abnormality present in the sciatic nerves was degeneration of about 40% of myelinated axons. Only occasional unmyelinated axons were degenerated. Figures were similar for nerves of either side and for both groups. Frequency histograms of axonal diameter showed axons of all sizes to be altered in group A, whereas in group B there was tendency for larger axons to be damaged. Electron microscopy showed no typical bullet-shaped viral particles. Asymptomatic animals which received the higher dose of the inoculum showed a small (less than 1%) percentage of necrotic myelinated axons.     

Role of transthyretin in posttraumatic regeneration of the sciatic nerve in mouse

Although thyroid hormones are known to have a significant influence on the development of nervous system, the absence of changes in the brain of mice deficient in transthyretin--a protein providing thyroid hormone transport across the blood-brain and blood-nerve barrier--remains unexplained. Therefore, the aim of this study was to determine the effect of transthyretin on the formation of myelinated and unmyelinated nerve fibers in sciatic nerve of mice. The myelinated and unmyelinated nerve fibers were counted in sciatic nerve of 3-months-old normal and transthyretin-knockout (transthyretin(-/-)) mice 15 and 30 days after nerve crushing. No differences were detected in the number of myelinated and unmyelinated nerve fibers in intact control (wild-type) animals group vs. transthyretin(-/-) mice. By days 15 and 30 after nerve crushing the number of myelinated nerve fibers was diminished by 54.7 and 71.8%, respectively, in transthyretin(-/-) mice, as compared to that in control animals. The number of unmyelinated nerve fibers at day 15 after the injury was not different in transthyretin(-/-) and control mice, however, by day 30 the number of these fibers in control group was found to increase significantly, exceeding that one in transthyretin(-/-) mice by 27.9%. These results indicate the important contribution of transthyretin, as a thyroxin carrier protein, to the process of posttraumatic regeneration of sciatic nerve. The absence of changes in nerve fiber numbers in transthyretin-knockout mice in postembryonic period suggests the presence of transthyretin-independent mechanism of thyroxin transport into the peripheral nervous system.     

大鼠坐骨神经超微结构的老年性变化

为了研究老年大鼠坐骨神经超微结构特点,随机取3月龄(成年组)和24月(老年组)龄正常SD大鼠各10只,用电镜观察两组间坐骨神经超微结构的差异。结果显示:老年组大鼠坐骨神经内有髓纤维的百分比、轴突间胶原纤维密度以及Schwann细胞胞质中脂褐质沉积密度均多于成年组(P<0.05);但无髓纤维之百分比少于成年组(P<0.05)。上述结果提示坐骨神经内的有髓纤维与无髓纤维百分比、轴突间胶原纤维密度以及Schwann细胞胞质中脂褐质沉积密度是衡量大鼠坐骨神经老化的形态标志之一。     

Effect of tetrapeptide cortagen on regeneration of sciatic nerve

Intramuscular injection of 10 μg/kg cortagen to rats during 10 days after transsection and suturing of the sciatic nerve increased the growth rate and conduction velocity in the regenerating nerve fibers by 27% and 40%, respectively. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 130, No. 12, pp. 654–656, December, 2000     

Structural changes in the peripheral nerves over a lifetime. Morphometric studies of the sciatic and sural nerves

Investigations were conducted on topographically identical tissue samples from the sciatic and sural nerves. 22 autopsies on individuals free of any severe disorder provided the material for this study (stillborn babies and deaths of unnatural causes). The material was selected with the view to having all age groups of human life represented. preferably two or more subjects of each decade. The overall cross-section and the cross-section of each bundle were planimetrically measured, using magnified photographs of celloidin sections, 30 micron in thickness. Depending on age, the sum of the cross-sections of all bundles was found to percentually decrease by about one fifth in all nerves relative to the overall cross-section. Alterations in the sural nerve and in the smaller portion of the sciatic nerve (N. peronaeus communis) were characterised by linear regression of measurements with a negative correlation, but non-linear regression could be estimated for the larger portion (N. tibialis). Semi-thin sections of methacrylate-embedded material were used to ascertain the numerical density of Schwann cell nuclei on all cases and to study fibre calibre distribution on three selected subjects. The averaged numerical density of Schwann cell nuclei decreased by about 80% from birth to the age of five years and varied between the second and fifth decades within a relatively small range described by a hyperbolic regression. No unambiguous correlation was found to exist beyond the fifth decade.(ABSTRACT TRUNCATED AT 250 WORDS)     

Problems with the use of the toe-spreading reflex in rats as an assay in nerve regeneration studies

Stages in the return of the toe-spreading reflex after sciatic nerve injury were examined using the rat. It was found that the earliest stages in the return of the reflex do not indicate nerve regeneration, but rather reflect the development of adrenalin sensitivity in denervated muscles. Probably systemic adrenalin released during the reflex-testing procedure causes muscle contractions which imitate a nerve-induced toe-spread reflex.     

负压吸引与大鼠损伤坐骨神经的修复和再生

背景：外周神经缺损的修复是目前创伤外科及修复重建外科临床上的一个难题,常用的神经移植、神经延长、神经桥接和组织工程等方法有局限性。 目的：比较不同负压对大鼠损伤坐骨神经的修复和再生。 方法：健康成年SD 大鼠分别以 6.65,13.30,19.95 kPa压力对大鼠右侧离断坐骨神经近端行负压吸引。负压每吸引60 min,休息30 min,交替进行,连续4周。 结果与结论：术后1个月,6.65,13.30,19.95 kPa负压吸引的大鼠坐骨神经实验侧近端均有不同程度生长,且 13.30 kPa压力组生长长度明显优于6.65和19.95 kPa组;对延长的神经进行组织学观察,发现延长神经的近侧部分轴突轴索较直,弯曲度较小,粗细均匀,髓鞘连续性良好,再生神经生长较好;中段部分神经纤维致密,成簇状排列,神经延长末端髓鞘成分减少,许旺细胞增殖明显。说明负压吸引可以促进大鼠坐骨神经的再生,且13.30 kPa压力下更有利于神经再生。     

Functional development of the visual system in normal and protein deprived rats. II. Morphometric and biochemical studies on adult optic nerve

The optic nerve of normal (C) and protein deprived (PD) adult rats was examined by morphometry and biochemistry. The mean cross-sectional area of the optic nerve was reduced by 15% and the number of axons per unit area increased by 17% in the PD rats. Calibre spectrum analysis of axons revealed a reduction in median diameter from 0.49 micron in controls to 0.45 micron in PD rats. The number of axons with a diameter larger than 1 micron was reduced by 35% in PD rats. These reductions were probably due to a general reduction in size, since the calculated total number of axons in the optic nerve was almost identical in C and PD rats (126 X 10(3) and 124 X 10(3), respectively). The increased packing density of axons in the nerve was not only due to thinner axons. The biochemical measurements showed a marked reduction in myelin basic protein in the optic nerves of PD rats, without an alteration in the composition of the total protein. This confirms the persistent hypomyelination which has been reported previously in other malnutrition models. The possible relations between the structural and biochemical changes affecting optic nerve fibres and physiological findings on cortical visual evoked response and on optic nerve in vitro in PD rats are discussed.     

Nimodipine effects on cerebral microvessels and sciatic nerve in aging rats.

At the ultrastructural level different anomalies of the cerebral microvasculature were encountered in the brains of aged rats. These aberrations can either be attributed to degeneration processes or to the perivascular deposition of, e.g., collagen fibrils and other, unidentified, proteinous debris. We previously reported that chronic treatment with the calcium antagonist nimodipine from 24-30 months especially reduced the incidence of aging-related microvascular deposits in the frontoparietal motor cortex of rats. The same drug treatment did not interfere with the degeneration of pericytes. The reduction of the microvascular depositions was, however, not consistent throughout different cortical layers. We now demonstrate that an earlier onset (16-30 months) of the drug application yields a prominent and consistent reduction of microvascular deposits for all cortical layers studied. The earlier onset of the drug treatment again did not influence the quantity of pericyte degeneration. The effect of long-term nimodipine treatment (16-30 months) was also examined in the sciatic nerve. Compared to young animals the sciatic nerve of aged control rats (30 months) showed a variety of alterations of myelinated fiber (MF) morphometry. Nimodipine treatment from 16-30 months did not significantly change these morphometric aging-related changes. Approximately 6% of the MF in aged rats display morphological myelin irregularities. After nimodipine application the frequency of these alterations was reduced, which was, however, only significant for partial demyelination known as myelin ballooning. These results indicate a consistent influence of nimodipine on cerebral microvessels, while there is only a moderate effect on the morphology of sciatic myelinated fibers during the aging process.     

Long-term reinnervation effects after sciatic nerve lesions in adult rats.

Transection of the sciatic nerve in adult rats induces drastic changes in hindleg muscles. Earlier, we demonstrated that the reinnervated soleus (SOL) muscle, 21 weeks after a transection mainly contains type II fibers. This is in striking contrast to normal muscle, which consists to 80% of type I muscle fibers. Also we observed 13.9% of the fibers to be polyneurally innervated. The problem of the present study is whether these changes are reversible after Longer survival periods. Therefore, the SOL was studied 60 weeks after transection and reconstruction by an autologous nerve graft. In six rats, we studied muscle fiber distributions by monoclonal antibodies, and innervation patterns by cholinesterase staining and AgNO3 impregnation. Still at 60 weeks, only 20% of the muscle fibers are of type I and this is similar to results at 21 weeks, indicating that no recovery to the normal has been reached by that age. Furthermore, 20% of the endplates in the reinnervated SOL were polyneurally innervated, but we also observed this in 10% of the endplates on the control side. These increases, compared to data at 21 weeks, are interpreted as an aging effect.     

Morphometric analysis of early regeneration of motor axons through motor and cutaneous nerve grafts.

Peripheral nerve damage is a frequent consequence of trauma, tumor surgery or diseases. Clinical results of functional reinnervation after the application of cutaneous grafts are still unsatisfactory. Differences in the extracellular matrix are considered to be one of the factors responsible for poor results of motor axon reinnervation through the cutaneous graft. To verify these differences, we compared morphological features of the motor axons regenerating through the graft prepared from the saphenous nerve and the motor branch of the femoral nerve. Eighteen female adult rats (Wistar) were used in experiments. The saphenous nerve, the femoral nerve, and its main motor branch were exposed under deep anesthesia with ketamine and xylazine. The nerve graft (10 mm) prepared from the saphenous nerve was applied between the stumps of the transected motor branch of the femoral nerve in the 6 rats. In the next 6 rats, the nerve graft (10 mm) harvested from the motor branch of the femoral nerve was inserted between stumps of the transected motor branch of the femoral nerve on the contralateral side. All rats were perfused with Zamboni's fixative solution 14 days after grafting. The samples of grafts and the intact motor branch (n = 6) were dissected and embedded in Durcupan ACM. Semithin sections stained with Toluidine Blue were used for morphometric analysis of myelinated axons by means of computer-assisted image analysis system. Ultrathin sections counterstained with uranyl acetate were viewed and photographed in an electron microscope. The number of myelinated motor axons showing early regeneration under conditions of the cutaneous and motor nerve grafts was similar. The diameter of axons and thickness of their myelin sheaths were significantly smaller when the axons regenerated into the saphenous nerve in contrast to the motor graft. Morphometric analysis of early regeneration of myelinated motor axons suggests that the cutaneous and motor branches of the femoral nerve provide different conditions not for the growth but for the maturation of motor axons.